This proposal describes a Program-Project grant designed to investigate AIDS-associated diarrhea and wasting syndrome. There are five research projects, which will be supported by five cores. The projects are designed to provide the following information: 1) describe the natural history of patients with HIV infection with respect to morbidity (the development of chronic diarrhea and wasting) and mortality; 2) determine the intestinal pathophysiology involved in the diarrhea and wasting; 3) discover the microbial etiologies of the diarrhea; 4) study immunological parameters that might result in susceptibility to infection and alter host metabolism to a catabolic state; and 5) investigate by means of double blind, placebo-controlled clinical trials, the efficacy of therapy in well characterized patients. Each one of these projects is interrelated with the others. All are supported by the cores, which provide a microbiology laboratory, clinical study unit for hospitalization of patients, a gastrointestinal function/metabolism laboratory, a biostatistics and data management unit, and an administrative structure capable of supporting the entire project. At the end of the five years, will know considerably more about every aspect of AIDS-associated diarrhea and wasting syndrome as it occurs in African patients.